Isolated Ultrafiltration is often the only technique which allows saving human lives in the context of intensive therapy both for resuscitation and in cardiology. Although the technique is simple, it is carried out with complex dialysis equipments, which imply not only handling problems, but also evident problems for their high purchase, managing and maintenance costs.
In order to remove liquids from hyperhydrated patients in critical cardiovascular conditions, this technique is preferred to standard hemodialysis, thanks its characteristic feature of low flow both of blood feeding and ultrafiltration. The absence of dialysis bath and the relative circulation and control systems makes possible to design an equipment for Slow Continuous Ultrafiltration (S, C. U-F.) for a review of this technique, see Merril, RH/. “The technique of slow continuous ultrafiltration. Steps to maintain fluid balance without hemodynamic instability”; J. Crit. IHn.; 1991 March; 6(3).-289-94.
U.S. Pat. No. 6,514,226 teaches the treatment of patients affected by Congestive Heart Failure (CHF) by means of perfusion of a hemofilter through a suitable peristaltic pump. A depression is applied to the filter, which produces an ultrafiltration liquid; the amount of removed ultrafiltration liquid depends on the level of cardiocirculatory overload.
A more complex system is disclosed in U.S. Pat. No. 6,685,664, wherein a machine for extracorporeal treatment of blood substantially comprises withdrawal and return pipes, a pump for blood transfer, a hemofilter and control devices. The pump and the hemofilter are separated and mounted on a device controlling system operation. This machine is then mounted on a wheeled trestle. The whole system can be easily moved near the patient, however the overall size is considerable and it is unsuitable for use outside a hospital. A similar system is shown in US 2004054315.
A general common knowledge of this field and, in particular, the above mentioned patent and non-patent references are referred to for a complete picture of the state of the art.
There is still the need to have available a portable device for blood ultrafiltration, which maintains the efficacy of the known devices and of dialysis machines and allows its use outside the hospital premises, for example at patient's home, in the ambulance, in emergency situations, for example in field hospitals, in natural disaster situations, rescue in wilderness or places difficult to reach. Another need is to minimize the length of connecting tubes between patient and device, so as to use less blood possible to prime the pump-filter system, and anyway reduce blood residence time outside blood circle.
The present invention is focused to solve the above mentioned problems by providing a device essentially formed by a hemofilter incorporated with the pumping system.